SOLIDARITY: Members of Congress and staffers gather outside the Capitol on Monday to observe a moment of silence for Arizona Rep. Gabrielle Giffords and other victims of the shooting rampage Saturday. (Associated Press) more >

For many in Rep. Gabrielle Giffords‘ southeastern Arizona district, guns are a way of life for hunting and protection while they’re working on their ranches in a part of the country that has become ground zero for smuggling.

But, to some East Coast lawmakers, that gun culture led to Saturday’s shooting rampage in Tucson, Ariz., which killed six and wounded the congresswoman and 13 others. Now two lawmakers have said they’ll push for tougher gun controls, including stricter limits on high-capacity ammunition magazines.

“The only reason to have 33 bullets loaded in a handgun is to kill a lot of people very quickly,” said Sen. Frank R. Lautenberg, New Jersey Democrat. “These high-capacity clips simply should not be on the market.”

The shooting, which shocked the nation and has sparked a renewed call for a more civil political debate, has also exposed long-festering regional divisions over whether gun regulation deters crime and improves public safety, or whether it leaves more people vulnerable to attack.

“If a guy had taken his car and rammed it through that crowd and ran [Mrs. Giffords] over, do you think we would be calling for change to registration on cars?” said Philip Van Cleave, president of the Virginia Citizens Defense League, a gun rights group. “Of course, there would not be — yet, just as many people could be killed with the same evil intent.”

The man charged with the shooting, Jared Lee Loughner, appeared shackled in court Monday to face federal charges that could carry the death penalty. He was ordered held without bond, as doctors said Mrs. Giffords, 40, was responding to verbal commands but remained in critical but stable condition.

At the White House, President Obama observed a moment of silence and then praised those who tackled the shooter and prevented him from continuing to fire.

“Part of what I think that speaks to is the best of America, even in the face of such mindless violence,” Mr. Obama said.

Authorities say the suspect used a 33-round magazine in his Glock 19 semiautomatic pistol, which allowed him to fire numerous bullets without having to manually reload. When his first magazine was empty and he tried to reload, two men tackled him, ending the killing spree.

Mr. Lautenberg and Rep. Carolyn McCarthy, New York Democrat, said they will introduce legislation aimed at reinstating part of the federal assault-weapons ban that from 1994 and 2004 barred the manufacture and sale of magazines that held more than 10 rounds at time.

“Before 2004, these ammunition clips were banned, and they must be banned again,” Mr. Lautenberg said.

Generally speaking, lawmakers from coastal states have been more supportive of strict gun-control laws as a way to improve public safety, and lawmakers from Southern and Western states have opposed stricter gun laws out of fear that they leave their constituents more vulnerable.

“It is not a surprise that Carolyn McCarthy and Frank Lautenberg in the Senate are both Easterners,” said Robert J. Spitzer, a political science professor at State University of New York at Cortland who specializes in gun-control studies.

A similar point was driven home last year after the Brady Campaign to Prevent Gun Violence, a Washington-based gun-control group, ranked Arizona second to last in state gun-control laws. Arizona is one of only three states to allow most residents to carry a concealed weapon without getting a permit.

Mrs. Giffords has said she considered herself a gun rights supporter and owns firearms, putting her in line with many of her constituents. The National Rifle Association gives her a mixed grade for her voting record.

But even in southeastern Arizona, gun control is an issue. Pima County Sheriff Clarence Dupnik, whose department handled the initial investigation into the shooting, lashed over the weekend at the region’s reputation for gunslinging, which extends all the way back to the Wild West days, when Wyatt Earp fought it out on the streets of Tombstone, which is in Mrs. Giffords‘ district.

“I think we’re the Tombstone of the United States of America,” Sheriff Dupnik said. “I have never been a proponent of letting everybody in this state carry weapons under any circumstances that they want, and that’s almost where we are.”

Every new mass shooting sparks the debate again, with the most recent round coming after a student killed 32 people at Virginia Tech in 2007.

The Supreme Court ruled last year that the Second Amendment establishes an individual’s right to bear arms, though it said that doesn’t rule out all restrictions.

Robert A. Levy, chairman of the Cato Institute’s board of directors and staunch defender of the Second Amendment, said that if a ban on high-capacity magazines is passed, it would have a “very good chance” of surviving a legal challenge.

Asked about the push to outlaw high-capacity magazines, Mr. Van Cleave said that the effort is more about scoring political points than improving public safety.

Even if the bill survives, Mr. Van Cleave predicted that curbing high-capacity magazines would do little to prevent people from getting their hands on such ammunition magazines.

“If a guy wants one, he will find one,” he said. “They were available all over the place during the Clinton years. They were a little more expensive, but they were certainly plentiful.”